/*
 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package javax.script;

import java.util.Map;
import java.util.HashMap;
import java.util.Collection;
import java.util.Set;

/**
 * A simple implementation of Bindings backed by
 * a <code>HashMap</code> or some other specified <code>Map</code>.
 *
 * @author Mike Grogan
 * @since 1.6
 */
public class SimpleBindings implements Bindings {

  /**
   * The <code>Map</code> field stores the attributes.
   */
  private Map<String, Object> map;

  /**
   * Constructor uses an existing <code>Map</code> to store the values.
   *
   * @param m The <code>Map</code> backing this <code>SimpleBindings</code>.
   * @throws NullPointerException if m is null
   */
  public SimpleBindings(Map<String, Object> m) {
    if (m == null) {
      throw new NullPointerException();
    }
    this.map = m;
  }

  /**
   * Default constructor uses a <code>HashMap</code>.
   */
  public SimpleBindings() {
    this(new HashMap<String, Object>());
  }

  /**
   * Sets the specified key/value in the underlying <code>map</code> field.
   *
   * @param name Name of value
   * @param value Value to set.
   * @return Previous value for the specified key.  Returns null if key was previously unset.
   * @throws NullPointerException if the name is null.
   * @throws IllegalArgumentException if the name is empty.
   */
  public Object put(String name, Object value) {
    checkKey(name);
    return map.put(name, value);
  }

  /**
   * <code>putAll</code> is implemented using <code>Map.putAll</code>.
   *
   * @param toMerge The <code>Map</code> of values to add.
   * @throws NullPointerException if toMerge map is null or if some key in the map is null.
   * @throws IllegalArgumentException if some key in the map is an empty String.
   */
  public void putAll(Map<? extends String, ? extends Object> toMerge) {
    if (toMerge == null) {
      throw new NullPointerException("toMerge map is null");
    }
    for (Map.Entry<? extends String, ? extends Object> entry : toMerge.entrySet()) {
      String key = entry.getKey();
      checkKey(key);
      put(key, entry.getValue());
    }
  }

  /**
   * {@inheritDoc}
   */
  public void clear() {
    map.clear();
  }

  /**
   * Returns <tt>true</tt> if this map contains a mapping for the specified
   * key.  More formally, returns <tt>true</tt> if and only if
   * this map contains a mapping for a key <tt>k</tt> such that
   * <tt>(key==null ? k==null : key.equals(k))</tt>.  (There can be
   * at most one such mapping.)
   *
   * @param key key whose presence in this map is to be tested.
   * @return <tt>true</tt> if this map contains a mapping for the specified key.
   * @throws NullPointerException if key is null
   * @throws ClassCastException if key is not String
   * @throws IllegalArgumentException if key is empty String
   */
  public boolean containsKey(Object key) {
    checkKey(key);
    return map.containsKey(key);
  }

  /**
   * {@inheritDoc}
   */
  public boolean containsValue(Object value) {
    return map.containsValue(value);
  }

  /**
   * {@inheritDoc}
   */
  public Set<Map.Entry<String, Object>> entrySet() {
    return map.entrySet();
  }

  /**
   * Returns the value to which this map maps the specified key.  Returns
   * <tt>null</tt> if the map contains no mapping for this key.  A return
   * value of <tt>null</tt> does not <i>necessarily</i> indicate that the
   * map contains no mapping for the key; it's also possible that the map
   * explicitly maps the key to <tt>null</tt>.  The <tt>containsKey</tt>
   * operation may be used to distinguish these two cases.
   *
   * <p>More formally, if this map contains a mapping from a key
   * <tt>k</tt> to a value <tt>v</tt> such that <tt>(key==null ? k==null :
   * key.equals(k))</tt>, then this method returns <tt>v</tt>; otherwise
   * it returns <tt>null</tt>.  (There can be at most one such mapping.)
   *
   * @param key key whose associated value is to be returned.
   * @return the value to which this map maps the specified key, or <tt>null</tt> if the map
   * contains no mapping for this key.
   * @throws NullPointerException if key is null
   * @throws ClassCastException if key is not String
   * @throws IllegalArgumentException if key is empty String
   */
  public Object get(Object key) {
    checkKey(key);
    return map.get(key);
  }

  /**
   * {@inheritDoc}
   */
  public boolean isEmpty() {
    return map.isEmpty();
  }

  /**
   * {@inheritDoc}
   */
  public Set<String> keySet() {
    return map.keySet();
  }

  /**
   * Removes the mapping for this key from this map if it is present
   * (optional operation).   More formally, if this map contains a mapping
   * from key <tt>k</tt> to value <tt>v</tt> such that
   * <code>(key==null ?  k==null : key.equals(k))</code>, that mapping
   * is removed.  (The map can contain at most one such mapping.)
   *
   * <p>Returns the value to which the map previously associated the key, or
   * <tt>null</tt> if the map contained no mapping for this key.  (A
   * <tt>null</tt> return can also indicate that the map previously
   * associated <tt>null</tt> with the specified key if the implementation
   * supports <tt>null</tt> values.)  The map will not contain a mapping for
   * the specified  key once the call returns.
   *
   * @param key key whose mapping is to be removed from the map.
   * @return previous value associated with specified key, or <tt>null</tt> if there was no mapping
   * for key.
   * @throws NullPointerException if key is null
   * @throws ClassCastException if key is not String
   * @throws IllegalArgumentException if key is empty String
   */
  public Object remove(Object key) {
    checkKey(key);
    return map.remove(key);
  }

  /**
   * {@inheritDoc}
   */
  public int size() {
    return map.size();
  }

  /**
   * {@inheritDoc}
   */
  public Collection<Object> values() {
    return map.values();
  }

  private void checkKey(Object key) {
    if (key == null) {
      throw new NullPointerException("key can not be null");
    }
    if (!(key instanceof String)) {
      throw new ClassCastException("key should be a String");
    }
    if (key.equals("")) {
      throw new IllegalArgumentException("key can not be empty");
    }
  }
}
